🔘prefer-number

🚧 under construction

JS ⟩ value ⟩ type ⟩ conversion ⟩ object -> primitive ⟩ prefer-number

• prefer-number：preferring a number (if conversion is possible)

🗺️ 圖表

💈範例

• replit："prefer-number" conversion

Number([]),      // ⭐ 0  ("prefer-number" conversion)
                 // -----------------------------------------------------
[].valueOf(),    // []    (1. array: an object, fall back to `toString`)
[].toString(),   // ''    (2. empty string, primitive accepted)
                 // 0     (3. '' converts to 0)

Number([8]),     // ⭐ 8  ("prefer-number" conversion)
                 // -----------------------------------------------------
[8].valueOf(),   // [8]   (1. array: an object, fall back to `toString`)
[8].toString(),  // '8'   (2. string, primitive accepted)
                 // 8     (3. '8' converts to 8)

Number([1,2]),   // ⭐ NaN   ("prefer-number" conversion)
                 // -----------------------------------------------------
[1,2].valueOf(), // [1,2]    (1. array: an object, fall back to `toString`)
[1,2].toString(),// '1,2'    (2. string, primitive accepted)
                 // NaN      (3. '1,2' converts to NaN)

👥 相關

• ⛔ "prefer-number" may result in ⛔️ TypeError❗

📗 參考

• JavaScript: The Definitive Guide ⟩

  • 3.9.2 Explicit Conversions

  • 3.9.3 Object to Primitive Conversions

  • 14.4.7

📘 手冊

• Object.prototype.toString() - object to string.

• Object.prototype.valueOf() - object to (primitive) value, if exists.